Circuit breaker control employing saturable reactors



J. BAUDE Dec. 31, 1963 CIRCUIT BREAKER CONTROL EMPLOYNG SATURABLE REACTORS Filed June 17, 1957 United States Patent O 3,116,440 CHRCUIT BREAKER CNTROL EMPLOYING SATURABLE REACTRS John Bande, Milwaukee, Wis., assigner to Allis-Chalmers Manufacturing Company, Milwaukee, Wis. Filed June 17, 1957, Ser. No. 666,068 2 Claims. (Cl. 317-54) This invention relates to electric control systems and more particularly to new and improved systems for closing circuit breaker structures which systems employ saturable reactors of one form or another.

The usual control in general use for closing electrically operated circuit breakers is what is called the XY relay scheme.` ln this scheme Y is a small control relay with a maintaining circuit which keeps closed until the breaker is completely closed and X is a control relay energized through the Y relay `to close a solenoid circuit.

In accordance with the invention claimed, the X and Y relays in the RY scheme are replaced with a saturable coil reactor which when energized by a push button or other control device causes a small amount oi direct current to ilow temporarily through a control winding on the saturable coil reactor causing the reactor to saturate and pass a suicient value of current to operate a closing coil or solenoid of a circuit breaker structure. On large circuit breakers the saturable reactor type of control may be cheaper to manufacture than the XY relay scheme while the speed of operation `of the former is faster than the speed of operation of the latter.

It is, therefore, one object of this invention to provide a new and improved control system for circuit breaker operation.

Another object of this 4invention is to provide a new and improved circuit breaker closing control system in which a saturable reactor is employed to control the energization of a closing coil.

A further object of this invention is to provide a new and improved control system for circuit breakers in which the speed of operation is faster than that obtained with a contacter.

A still further object of this invention is to provide a new and improved control system for large circuit breakers which may be cheaper to manufacture and use than the presently used control contactors.

And still another object of this invention is to provide a new and improved static control system for large circuit breakers which eliminates all auxiliary relays and contacts directly associated with circuit breaker closing coil energization.

Objects and advantages other than those set forth will be apparent from the following description when read in connection with the accompanying drawing, in which:

FIG. l illustrates a circuit breaker control .system embodying magnetic amplifier for closing a circuit breaker and employing the invention; and

FIG. 2 is a partial view of FIG. l illustrating a modiiication of the control system shown in FG. l.

Referring more particularly to the drawing by characters of reference, FIG. l shows an alternating current supply circuit 1 controlled by a circuit breaker 2. The circuit breaker is controlled by a closing solenoid coil 3 and a tripping solenoid coil 4. The closing coil 3 is energized through a closing circuit comprising a saturable reactor shown in FIG. l as a magnetic ampliiier 5 comprising a pair of cores 6 and 7 of magnetic material, preferably of a material having a relatively high permeability. On core 6 is wound a reactance winding 8 and on core 7 is wound a reactance winding 9. Linking both cores are a direct current control or input winding 1i] and a direct current compensating or biasing winding 11.

Reactauce windings y8 and 9 'are connected in parallel with each other between the supply circuit 1 and the closing coil 3. In series with windings 8 and 9 are the unidirectional current conducting devices 12, 13, 14 and 15. These devices, which :may be of any suitable type such as conventional alternating current copper oxide rectiers or silicon diodes, are reversely connected 'with respect to current iiow in the supply and load or closing circuits so that, for example, positive half cycles of load current ow through winding d and negative half cycles of load current liow through winding 9. In this manner only pulsating unidirectional current can ow sequentially in each of the reactance windings S and 9. In addition, these reactance windings are so wound or connected on their respective cores that the pulsating unidirectional -uxes which they produce are in the same direction with respect to that portion of 4the cores 6 and '7 surrounded by input and biasing windings 1t) and 11. The control winding 1i) which is connected in series with a capacitor 31 and a discharge resistor 32, both connected in parallel with each other, is adapted to have direct current pulses circulated therein of such a polarity that the flux produced by this winding will have the same direction in the parts of cores e and 7 surrounded therewith as the iluxes produced by the reactance windings 8 and 9. The biasing winding 11 is adapted to have a substantially constant value of direct current circulated therein of such a polarity that the flux produced by this winding will be in opposition to the direction of the fluxes produced by reactance windings 8 and 9 in the parts or cores 6 and 7 surrounded by winding 11.

Although a magnetic ampliiier is shown in FIG. l of the drawing, this disclosure is intended to disclose the invention as related to any form of saturable reactor which the magnetic ampliiier is merely one form thereof. Further, the drawing illustrates two cores each having a part thereof surrounded by the control and biasing windings 1@ and 11; however, it is intended that a single core structure may be used having a common leg thereof surrounded by windings 1d and 11.

Upon closing push button switch 16 current flows from conductor 1a of the source of supply 1 through conductors 17 and 1S, push button switch 16, lfull -wave rectiiier 19, conductor 2i), capacitor 31, control winding 1t) of magnetic amplifier 5, conductor 21, rectifier 19 and conductors 2.2 and 23 to conductor 1b. The control winding 1d may be part oi the self-saturated magnetic amplitier system shown on the drawing involving selfsaturat ing rectitiers 12, 13, le and 15 or may be a part of a saturable reactor. ln case of a saturable reactor the selfsatnrating rectiers are omitted and the control winding requires more power to `drive the amplifier to saturation than with the magnetic ampliiier shown.

Compensating or biasing winding 11 is energized by a full wave rectiiier Z6. Rectiiier 26 is connected across conductors 1a and 1b of the supply 1 through conductor 17 on one side thereof and conductors 27 and 23 on the other side thereof. Biasing winding 11 decreases the saturation of cores o and 7, thereby preventing all but a negligible current to flow therethrough and closing coil 3 of circuit breaker 2 when reactance windings 8 and 9 `are energized through rectifiers 12, 13, 14 and 15, and control winding 11i is deenergized.

If now direct current is caused to flow temporarily in the control winding 1d, the saturation of the cores 6 and 7 will be increased again to permit current iiow through windings 8 and 9. Temporary control current flow is assured by the introduction of capacitor 31 and discharge resistor 32, the function of which is such that the discharged capacitor passes current the moment push button 16 is closed. Current ilow will be substantially reduced when the capacitor is fully charged. This provides for antipumping control in case the circuit breaker should close on a short circuit. If the closing push button 16 is reclosed, the capacitor will discharge through discharge resistor 32 and the control then is ready for another closing operation. The reduction in saturation of the cores 6 and 7 increases the self-induced countervoltages in the reactance windings S and 9 so that the reactance voltage drop across these windings is increased and less current is permitted to ilow through the load circuit including the closing coil 3 of circuit breaker 2. If the direct current input to the control winding 10 is such that it causes saturation of cores 6 and 7 beyond the knees of their respective saturation curves, the reactance or windings 8 and 9 will be reduced so far that substantially all of the supply voltage will be across closing coil 3 and a very small percentage of it will appear across the reactance windings 8 and 9, thereby causing current to iiow through coil 3 of suiicient value to close the circuit breaker 2.

The main advantage of using a saturable reactor or magnetic amplifier as compared with the conventional closing contactor and relays is that the amplier can be designed for greater speed, therefore materially reducing the closing time of the circuit breaker. Further, these devices eliminate the unreliable contacts of the auxiliary relays. The saturable reactor and the magnetic amplier can raise the load current through the closing coil of the circuit breaker from a minimum to a maximum value in a shorter time than the conventional contactors. For practical application, as well known in the art, it may be advisable to use means for temporarily shunting the contacts of the closing push button switch 16 until the circuit breaker has actually completed its closing operation.

The circuit breaker 2 is biased to open position by means of an accelerating spring 40. Contacts 2a, 2b, 2c and 2d of breaker 2 are supported by a rod 41. Breaker rod 41 is pivotally connected at 42 to a trip free operating linkage 44. The operating linkage 44 comprises a lever 4S pivoted at 46 and a lever 47 pivoted at 43. The levers 45 and 47 are interconnected by a toggle comprising two toggle elements 49 and Sil. Toggle element 49 is pivotally connected to lever 47 by a pin carrying a roller 51 and toggle element Sti is pivotally connected at 52 to lever 45. Toggle elements 49 and 50 are pivotally joined together by a pin 53. Pin 53 supports a roller 54 which is acted upon by an operating ram S.

In the contact closed position of the operating linkage 44 the upper position of pin 53 and roller 54 is controlled by an abutment 56. This abutment is made of any suitable resilient material and is adapted to minimize vibrations of the frame of the trip free mechanism due to the impact of linkage 44 upon abutment 56. In the closed position of the circuit breaker 2 pin 53 forming the joint or connection between toggle elements 49 and 50 is supported by a spring biased prop 57.

The circuit breaker 2 is tripped open upon a predetermined movement of the armature of the tripping coil 4 upon closing push button switch 28. Tripping coil 4 actuates a pivotally mounted lever 58. Upon rotation of lever 58 about its pivot point in the counterclockwise direction, lever 58 causes counterclockwise movement of lever 47 followed by collapse of the toggle formed by toggle elements 49 and Si) and return of lever 47 to the position shown to cause the separation of the circuit breaker contacts.

In order to close the circuit breaker 2 and to reset the operating linkage 44, the operating ram 55 is actuated upward by any suitable means such as a iiuid motor (not shown) causing return of toggle elements 49 and Sil to their overcenter position where they are held by the spring biased prop' 57.

FIG. 2 illustrates a saturable reactor having the reactance windings 8 and 9 and the control winding 19 mounted on a core structure 60. These windings are connected in the manner shown to conductors 17, 20, 21 and 23 and closing coil 3 of the control system shown in FIG. 1. In this illustration the reactance windings 8 and 9 are provided with alternating current from source 1 and the control winding 1li with direct current from the full wave rectifier 19. Windings 8 and 9 are so wound on core 6@ that the fluxes produced thereby are in opposite directions in the common leg 61 of the core structure 69. Upon the energization of control winding 10 in the manner described for FiG. 1 the flux produced by winding 19 will cause the core 69 to saturate and current to ilow through closing coil 3 to close the circuit breaker 2.

Although but two embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

What is claimed is:

l. In combination a circuit breaker, a closing coil for actuating said breaker, a core structure of magnetic material, a pair of reactance windings mounted on said core structure and connected in series with said coil, means for energizing said pair of windings, said reactance windings during unsaturated condition or said core structure limiting current ow through said coil to retain said coil in the de-enerized condition, a control winding mounted on a part of said cord structure, a source of unidirectional current, and capacitance means connecting said source to said control winding for supplying said control winding with a single pulse of unidirectional current causing said core structure to reach saturation and current to flow through said coil of sufiicient value to close said breaker.

2. In combination, a circuit breaker, a ciosing coil for actuating said breaker, a core of magnetic material, a pair of reactance windings mounted on said core and connected in parallel with each other and in series with said coii, means for sequentially energizing said pair of windings each with half wave rectified current, a control winding mounted on said core, means for supplying said control winding with a single pulse of unidirectional current, said means comprising a capacitor and a discharge resistor, Said resistor being connected in parallel with said capacitor and in series with said control winding, said resistor discharging said capacitor during the time said control winding is deenergized, a compensating winding mounted on said core, means for supplying said compensating winding with a substantially constant value of unidirectional current, the magnetomotive forces of said reactance windings and said control winding being in the same direction with respect to each other and opposite in direction with respect to the magnetomotive force of said compensating winding, said control winding when supplied with unidirectional current causing said core to reach saturation and current to ilow through said coil of sufficient value to close said breaker.

Reterences Cited in the tile of this patent UNITED STATES PATENTS 2,667,143 Logan Jan. 5, 1937 2,247,983 Barth July l, 1941 2,329,082 Reagan Sept. 7, 1943 2,394,039 Brown Feb. 5, 1946 2,482,524 Vrooman Sept. 20, 1949 2,677,800 Phillips May 4, 1954 2,743,492 Easton May l, 1956 2,757,320 Schuh July 3l, 1956 2,807,776 Buechler Sept. 24, 1957 2,977,511 Reeder et al. Mar. 28, 1961 FOREIGN PATENTS 481,054 Great Britain Mar. 4, 1938 

1. IN COMBINATION A CIRCUIT BREAKER, A CLOSING COIL FOR ACTUATING SAID BREAKER, A CORE STRUCTURE OF MAGNETIC MATERIAL, A PAIR OF REACTANCE WINDINGS MOUNTED ON SAID CORE STRUCTURE AND CONNECTED IN SERIES WITH SAID COIL, MEANS FOR ENERGIZING SAID PAIR OF WINDINGS, SAID REACTANCE WINDINGS DURING UNSATURATED CONDITION OF SAID CORE STRUCTURE LIMITING CURRENT FLOW THROUGH SAID COIL TO RETAIN SAID COIL IN THE DE-ENERGIZED CONDITION, A CONTROL WINDING MOUNTED ON A PART OF SAID CORD STRUCTURE, A SOURCE OF UNIDIRECTIONAL CURRENT, AND CAPACITANCE MEANS CONNECTING SAID SOURCE TO SAID CONTROL WINDING FOR SUPPLYING SAID CONTROL WINDING WITH A SINGLE PULSE OF UNIDIRECTIONAL CURRENT CAUSING SAID CORE STRUCTURE TO REACH SATURATION AND CURRENT TO FLOW THROUGH SAID COIL OF SUFFICIENT VALUE TO CLOSE SAID BREAKER. 